After reading about someone venting their Lindsey CBV to air, I figured I'd give it a try too. I thought it could be interesting to mount the CBV like stock to see if there is any difference. (I suspect the valve leaks when mounted opposite of stock. It will not clear the hood if I install it like the stock valve).

Here's what I discovered:
The amount of air escaping from the valve when I suddenly close the throttle is surprisingly large. I tried this with the car at idle. I imagine the amount when the car is under boost of considerably larger.
Anyways, I tried venting to air with the valve installed like stock (opposite of how Lindsey says to install it). The car would almost die whenever I revved and closed the throttle.
I assume this is because the car runs seriously rich when I vent to atmosphere(??).

So I decided to mount the valve as Lindsey says to see if the valve behaves the same. I plugged the hole in the J-boot and let the valve vent to atmosphere.
When I did this, the idle would fluctuate between 800rpms and 1500rpms.
I assume this is because the valve leaks (like I suspected) when it is mounted like Lindsey suggests.

My conclusion is that Lindsey’s valve is crap.

Would anyone care to comment?

 

Doesn't the air being vented have to be plumed back into the intake past the AFM or MAF because it has already been measured? If you vent to atmosphere then it looses that air that it already calculated fuel for and you get a rich condition?
Just some ideas, I have never tried venting to atmosphere but that sounds like what could be happening. Since your testing, see what happens when its plumed back in after the AFM/MAF.

 

How did you get the cbv to fit once you plugged that hole?
I'm trying to figure out a way to mount mine, but can only get it to fit if I place the valve upside down.
Will keeping it upside down affect its operation?

 

Schnellfahrer, why assuming that it leaks at idle when you have the opportunity to check it easily by putting your hand onto the open end. Furthermore, how can you build boost by just some free revving?

At idle, it doesn't matter how you have installed it. When I look at the valve, if it leaks, it should leak both ways. If you provide some vacuum to the small port the valve opens quite easily.

If you want to make more difficult to open at vacuum, increase the spring pressure. You do know that you can increase it by adding a couple of washers, to make it more difficult to open de valve?

BTW it's a TurboXS Bypass Valve. Lindsey just sells them.

I'm not sure whether or not the following is correct, but when I think about it, as long as there is vacuum it might be better to have the valve open. In that case the engine can suck in the air more freely, so it should rev easier, because the path the air has to travel is much shorter. This also could improve the spool up time. If the valve leaks when your on boost, then you're having an issue.

I think the problem arrises when you use it as a blow off valve instead of a bypass valve. In that case the amount of air sucked through the bypass valve doesn't go through the AFM/MAF and when you're coming off boost, you loose air that is already measured by the AFM/MAF.

 

Thanks for the feedback guys. There were a few things I wanted to know.

1. How much of a rich condition would one create by venting to atmosphere. Obviously rich enough to almost kill the engine.

2. Does the valve work differently depending on which way it is installed. Obviously it does since installing it one way caused a massive leak (fluctuating idle must be because of leak right? Or?) installing it another way and it idled fine.

This is why I think it leaks.
When installed the way Lindsey says, the air exiting the intercooler heading for the throttlebody will apply pressure to the piston in the valve in the direction the piston moves when the valve opens. When I installed it this way and vented to atmosphere, idle fluctuated. Why?

When installed oposite of what Lindsey says, the air exiting the intercooler heading for the throttlebody will apply pressure to the piston in the valve in the direction the piston moves when the valve closes. When I installed it this way and vented to atmosphere, it idled fine.

This is why I think installing it like suggested by Lindsey causes a leak; meatered air is leaking from the valve. When connected to the J-boot, this air is recirulated and idle is fine, but when vented to atm, this air is lost and you get a rich condition.

.
I don't think you can, but these are the results I got. The amount of air released by the cbv when just free revving was suprisingly large. Not enough to cause the psst-sound, but enough to feel it quite well with my hand.
That is true, but shouldn't I get the same result regardless of how I install the valve?

I have installed all the shims that came with the valve.

I'm not here to teach, but to learn.

 

First, venting to the atmosphere doesnt make that huge of a rich condition. It is only when you jump back on the throttle after shifting and only lasts for a split sec. I dont think you could notice the change. Second, when the stock diverters are on, they are used with vaccum. When you put Lindseys on backwards, just the pressure from the turbo...the boost, in the charge pipe could easily make it leak. You would have more of a leak problem the more boost you ran. Install Lindseys the way the stock unit is installed. Also, are you sure you plugged the hole to the intake boot well? Good luck

 

Thanks for your input Derek.
If venting to atm. doesn't cause a huge rich condition, why would my car almost stall when free revving?

Lindsey's valve will not clear the hood when installed like the stock valve (and I have a tiny dent to prove it).
Lindsey says to install it opposite.

I see we agree on the part of Lindsey's valve leaking when on boost.

I'm sure I plugged the hole in the J-boot well.

 

Eivind, I had the same issue, they have pics of one orientation on their site and say another... its confusing, I dont think they know themselves! I vented my LR to atm, and I would got surge, so it would not expell enough air. I sold mine... The unit they sell is a cheap generic unit, I found this out when I went to a mates place to try another because my LR unit was not venting well enough, and he had the exact same unit on his Evo3 and paid stuff all! Anyways, we tried loading some washers in but it was still not suitable for my application. It worked ok on my stock setup though, it was a litter louder...

 

Well, I'll be trying a different valve to see if there is a difference. I feel really stupid for buying into the hype and blowing $190 on the Lindsey modified valve.
I feel I can't sell it either. I'd just be screwing someone.
Oh well. Live and learn.

 

A CBV is supposed to "leak" when there's vacuum in the manifold... the idea is to allow intake air to bypass the turbocharger and the intercooler, hence the name "compressor bypass valve"

 

I sold mine cheap to a guy I knew had a standard setup...

I know how you feel though... I fell for it too, you are not the first though, and at least you didnt buy their 363 kit! It even took 4 emails to confirm which way it was supposed to go up!

 

schnellfahrer

Your bypass valve is supposed to pass air through it or be open when your car is idling. When you connect either ours, our the stock bypass valve to a vacuum line, it opens. When you car is idling, you have air bypassing through the valve circulating in your intake system. When you loose the vacuum, or go into boost, it closes and stays closed. When you place the valve into your hard pipe, and connect your vacuum line to it, and vent to atmosphere, the valve opens and you have created a large un-metered air leak. It surprises me you car idles at all. It should die right away or very quickly
like having a hard pipe disconnected.

It's working just like it's supposed to.

Also... it's supposed to be lying down. Opposite of the stock valve. When you have pressure on the
bottom of the piston under boost, you also have the same pressure on the opposite side of the piston
holding it closed because your vacuum line is under boost. In addition, your spring is assisting in
keeping it closed. When you lift the throttle, the boost in the vacuum line goes away instantly because your manifold vacuum dropped but you still have boost pressure in your hard pipes to the
bypass valve piston. This way, the greater pressure wins and slams the valve open for immediate bypassing. When you connect it to the side hole, only the vacuum will open it without
the assistance of the pressure on the end of the piston. Once the piston opens off the seat, it's
reasonable to assume you get pressure on the end of the piston and it lifts but that's not the way
to install it for the best results.

To confirm this, take your old bypass valve in your hand and connect it to a vacuum line on your
car when idling. It will open and stay open until you blip the throttle and the vacuum drops.

Wes

 

Thanks Wes. That is good information.
I can see how mounting it lying down with pressure on the piston can help it open quicker. I didn't think of that. The reason I questioned the functinality of the valve was that I expected a large improvement in spoolup and less lag after replaceing the broken stock valve. The difference was hardly noticeable.